Interesting thread you have started here naiveclone! I think it resonates with many starting out on their first tour.
Someone once said that travel can be dangerous but routine is fatal!
I was about your age 30 years ago and on a whim bought a 6 month round the world ticket leaving in two weeks. I told my parents the week before and headed off on my own. There was no chance to feel much fear as I was committed to leaving. I had just finished a job and I suppose was feeling like you. In the end I had a ball, met a lovely girl, travelled extensively overland through South East asia and China to Pakistan and eventually emigrated with her to Australia. Wasn't a cycle trip though!
That small decision led to a 12 year wonderful adventure of travel and fun. So go for it! I don't see your situation as sad but extremely exciting and an opportunity not to be lost.
There are some great web sites on cycle touring ... here are some articles from Alastair Humphreys about fear ...
http://www.alastairhumphreys.com/?s=fear&submit=SearchI recommend too that you read his two books about cycling round the world. They inspired me two years ago to cycle round the 6700km North Sea Cycle Route. True to form I bought a one way ticket from Shetland to Bergen in Norway two weeks hence so I had no choice but to leave. Again a wonderful three months, had a battery stolen , but no real problems.
Tom Allen is also a wonderful resource ...
http://tomsbiketrip.comHis book Janapar is also an inspirational read for someone contemplating a big cycle tour.
I mention Alastair Humphreys and Tom Allen as they seem to match your age and predicament. They have both overcome the fear of setting off and are great writers. Hope you find some more inspiration from them.
As for equipment, that Thorn bike on eBay looks just the job. I got almost all my stuff from eBay including my second hand Raven Tour from Thorn themselves.
So, just do it. Setting off is more important than having the latest newest fanciest gear, though I would not compromise on a good bike. A Thorn will do the job well!